|Out of universe information|
The Sheftu (pronounced "shef-too") are secondary recruits in the Tlak'kahn army. They appear to be transparent and their external skin seems to vary from pink, gray and purple. They have two organ sacks which seem to be connected by nerve synapses. One seems to contain most of their organs and the other one contains their brain. However they do not have any digestive or respiratory system.
As can be seen with Nephestis, the Sheftu's shape-shifting abilities make them suitable for serving as spies. However, in order to do this, they need a sample of the victim's DNA. They can do this simply by touching the victim's skin, but the DNA sample only remains in memory momentarily. Therefore, a Sheftu will have to get another DNA sample if it wants to represent the victim again.
The Ancients are able to distinguish between someone and a Sheftu impersonating that person.